The present invention relates generally to heterocyclic substituted pyrazolones, including pharmaceutical compositions, diagnostic kits, assay standards or reagents containing the same, and methods of using the same as therapeutics. The invention is also directed to intermediates and processes for making these novel compounds.
Protein kinases play a critical role in the control of cell growth and differentiation. Aberrant expression or mutations in protein kinases have been shown to lead to uncontrolled cell proliferation, such as malignant tumor growth, and various defects in developmental processes, including cell migration and invasion, and angiogenesis. Protein kinases are therefore critical to the control, regulation, and modulation of cell proliferation in diseases and disorders associated with abnormal cell proliferation. Protein kinases have also been implicated as targets in central nervous system disorders such as Alzheimer""s disease, inflammatory disorders such as psoriasis, bone diseases such as osteoporosis, atheroscleroses, restenosis, thrombosis, metabolic disorders such as diabetes, and infectious diseases such as viral and fungal infections.
One of the most commonly studied pathways involving kinase regulation is cellular signaling from receptors at the cell surface to the nucleus. Generally, the function of each receptor is determined by its pattern of expression, ligand availability, and the array of downstream signal transduction pathways that are activated by a particular receptor. One example of this pathway includes a cascade of kinases in which members of the Growth Factor receptor Tyrosine Kinases deliver signals via phosphorylation to other kinases such as Src Tyrosine kinase, and the Raf, Mek and Erk serine/threonine kinase families. Each of these kinases is represented by several family members which play related, but functionally distinct roles. The loss of regulation of the growth factor signaling pathway is a frequent occurrence in cancer as well as other disease states. Fearon, Genetic Lesions in Human Cancer, Molecular Oncology, 1996, 143-178.
The raf1 serine/threonine kinase can be activated by the known oncogene product ras. The raf kinase enzyme positively regulates cell division through the Raf/MEK/ERK protein kinase cascade. This activation is the result of cRaf1 catalyzed phosphorylation of the protein kinase, MEK1, which phosphorylates and activates the protein kinase ERK. ERK phosphorylates and regulates transcription factors required for cell division. Avruch et al., TIBS, 1994 (19) 279-283. cRaf1 negatively regulates cell death by modulation of the activity of Bcl-2, a critical regulator of apoptosis. This regulation involves direct phosphorylation of Bcl-2 family members. Gajewski and Thompson, Cell, 1996 (87) 619-628.
These aspects of cRaf1 -mediated regulation of cell proliferation require the kinase activity of cRaf1. It has also been reported that the reduction of Raf protein levels correlates with a reduction in tumor growth rate in vivo tumor mouse models. Monia, Johnston, Geiger, Muller, and Fubro, Nature Medicine, Vol. 2, No. 6, June 1996, 668-674. Inhibitors of the kinase activity of cRaf1 should therefore provide effective treatment for a wide variety of human cancers.
Activation of the MAP kinase signaling pathways represents an attractive target for tumor therapy by inhibiting one or more of the kinases involved. An additional member of the MAP kinase family of proteins is the p38 kinase, alternatively known as the cytokine suppressive drug binding protein or reactivation kinase, RK. Activation of this kinase has been implicated in the production of proinflammatory cytokines such as IL-1 and TNF. Inhibition of this kinase could therefore offer a treatment for disease states in which disregulated cytokine production is involved.
The signals mediated by kinases have also been shown to control cell growth, cell death and differentiation in the cell by regulating the processes of the cell cycle. Progression through the eukaryotic cell cycle is controlled by a family of kinases called cyclin dependent kinases (CDKs). The loss of control of CDK regulation is a frequent event in hyperproliferative diseases and cancer.
Inhibitors of kinases involved in mediating or maintaining particular disease states represent novel therapies for these disorders. Examples of such kinases include inhibition of Src, raf, and the cyclin-dependent kinases (CDK) 1, 2, and 4 in cancer, CDK2 or PDGF-R kinase in restenosis, CDK5 and GSK3 kinases in Alzheimers, c-Src kinase in osteoporosis, GSK-3 kinase in type-2 diabetes, p38 kinase in inflammation, VEGF-R 1-3 and TIE-1 and -2 kinases in angiogenesis, UL97 kinase in viral infections, CSF-1R kinase in bone and hematopoetic diseases, and Lck kinase in autoimmune diseases and transplant rejection.
Thus, there is a need for novel classes of compounds which demonstrate activity toward receptor and non-receptor types of protein kinases. It has been discovered that a class of compounds, referred to herein as heterocyclic-substituted pyrazolones, are useful as agents for the regulation of protein kinase. The present invention is therefore directed to, inter alia, their use as therapetic agents for the treatment of the foregoing disorders.
Accordingly, one object of the present invention is to provide novel compounds which are kinase inhibitors. In certain objects, the compounds of the present invention are inhibitors of one or more of vascular endothelial growth factor receptor (VEGFR) kinase, trkA tyrosine kinase (trkA), mixed lineage kinase (MLK) or fibroplast growth factor receptor kinase (FGFR).
It is another object of the present invention to provide pharmaceutical compositions comprising a pharmaceutically acceptable carrier and a therapeutically effective amount of at least one of the compounds of the present invention, or a pharmaceutically acceptable salt form thereof.
It is another object of the present invention to provide a novel method for treating or preventing disorders associated with the aberrant activity of protein kinases. In certain objects, the disorders are characterized by the aberrant activity of one or more of the vascular endothelial growth factor receptor (VEGFR) kinase, trkA tyrosine kinase (trkA), mixed lineage kinase (MLK) or fibroplast growth factor receptor kinase (FGFR), and the method comprises administering to a host in need of such treatment or prevention a therapeutically effective amount of at least one of the compounds of the present invention.
It is another object of the present invention to provide a method for inhibiting protein kinases in a body fluid sample. In certain objects, the method comprises treating the body fluid sample with an effective amount of at least one of the compounds of the present invention to inhibit one or more protein kinases.
It is another object of the present invention to provide a kit or container containing at least one of the compounds of the present invention in an amount effective for use as a diagnostic, standard or reagent.
These and other important objects, which will become apparent during the following detailed description, have been achieved by the inventor""s discovery that compounds of Formula I: 
stereoisomeric forms, mixtures of stereoisomeric forms, or pharmaceutically acceptable salt forms thereof, wherein R1, R2, R3, R4, R5, and Het are defined below, are effective kinase inhibitors.
Thus, in a first embodiment, the present invention provides a novel compound of Formula I: 
or a stereoisomer or pharmaceutically acceptable salt thereof, wherein:
Het is a heterocycle;
R1 is selected from H, C1-10 alkyl substituted with 0-5 R6, C2-8 alkenyl substituted with 0-5 R6, C2-8 alkynyl substituted with 0-5 R6, NRaRa, C(xe2x95x90O)Rb, C(xe2x95x90O)NHRa, CO2Rc, and heterocycle substituted with 0-5 R6;
with the provisos that when R1 and Het are both 2-pyridinyl, R2 and R3 are other than 4-diethylamino-2-phenyl; and when R1 is 4-carboxy-phenethyl, Het and either R2 or R3 are other than both dimethylamino-thiophene;
R2 and R3 are independently selected from H, C1-2 alkyl substituted with 1-5 R6, C3-10 alkyl substituted with 0-5 R6, C2-8 alkenyl substituted with 0-5 Ri, C2-6 alkynyl, Cl, Br, I CN, (CH2)rNRaRa, (CH2)rORc, (CH2)rSRc(CH2)rC(xe2x95x90O)Rb, (CH2)rCO2Rc, (CH2)rOC(xe2x95x90O)Rb, (CH2)rC(xe2x95x90O)NRaRa, (CH2)rNRaC(xe2x95x90O)Rb, (CH2)rNRaC(xe2x95x90O)ORb, (CH2)rOC(xe2x95x90O)NHRa, (CH2)rNRaS(xe2x95x90O)2Rb, (CH2)rS(xe2x95x90O)2NRaRa, (CH2)rS(O)pRb, (CH2)rcarbocycle substituted with 0-5 R4, and (CH2)rheterocycle substituted with 0-5 R4;
with the provisos that R2 and R3 are other than both H or both SMe; and when R2 is H, and R3 is phenyl, Het is not 2-furanyl;
alternatively, R2 and R3 join to form a heterocycle substituted with 0-4 R4, with the proviso that the heterocycle is other than 2-thiazolidinyl or 5-methyl-2-oxazolidinyl;
R4, at each occurrence, is independently selected from H, F, Cl, Br, I, CN, CF2CF3, CF3, NO2, CN, OH, NRaRa, ORc, C(xe2x95x90O)Rb, CO2Rc, OC(xe2x95x90O)Rb, NRaC(xe2x95x90O)Rb, C(xe2x95x90O)NRaRa, OC(xe2x95x90O)NRaRa, NRaC(xe2x95x90O)Rb, NRaS(xe2x95x90O)2Rb, S(xe2x95x90O)2NRaRa, NRaC(xe2x95x90S)Rb, C(xe2x95x90S)NRaRa, NRaC(xe2x95x90O)NRaRa, NRaC(xe2x95x90S)NRaRa, CHxe2x95x90NORc, CHxe2x95x90NRa, CHxe2x95x90NNRaRa, (CH2)rS(O)pRb, O(CH2)qNRaRa, O(CH2)qORc, (CH2)rORd, (CH2)rC(xe2x95x90O)Rdxe2x80x2, (CH2)rNHRd, (CH2)rS(O)pRdxe2x80x2, C1-10 alkyl substituted with 0-5 R6, C2-8 alkenyl substituted with 0-5 R6, C2-8 alkynyl substituted with 0-5 R6, carbocycle substituted with 0-5 R6, and heterocycle substituted with 0-5 R6;
R5 is either absent or is selected from H, C1-8 alkyl, C2-6 alkenyl, C2-6 alkynyl, (CH2)rC3-6 cycloalkyl, and (CH2)rphenyl;
R6, at each occurrence, is selected from C1-6 alkyl substituted with 0-5 Rh, C2-8 alkenyl, C2-8 alkynyl, F, Cl, Br, I, CN, CF2CF3, CF3, NO2, CN, NRfRf, ORf, C(xe2x95x90O)Rf, CO2Rf, OC(xe2x95x90O)Rg, NRfC(xe2x95x90O)Rf, C(xe2x95x90O)NRfRf, OC(xe2x95x90O)NRfRf, NReC(xe2x95x90O)ORg, NReS(xe2x95x90O)2Rg, S(xe2x95x90O)2NRfRf, NRaC(xe2x95x90S)Rg, C(xe2x95x90S)NRfRf, NRfC(xe2x95x90O)NRfRf, NRfC(xe2x95x90S)NRfRf, CHxe2x95x90NORe, CHxe2x95x90NRe, CHxe2x95x90NNReRe, S(O)pRf, O(CH2)pNRfRf, O(CH2)pORf, ORd, NHRd, C(xe2x95x90O)Rdxe2x80x2, S(O)pRdxe2x80x2, carbocycle substituted with 0-5 Rh, heterocycle substituted with 0-5 Rh, P(xe2x95x90O)(ORc)2, and a C5-7 monosaccharide wherein each hydroxyl group of the monosaccharide is unsubstituted or replaced by a group selected from H, C1-4 alkyl, C1-4 alkoxy, and OC(xe2x95x90O)C1-4 alkyl;
Ra, at each occurrence, is independently selected from H, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, (CH2)rC3-6 cycloalkyl, and (CH2)rphenyl, wherein when Ra is other than H, Ra is substituted with 0-5 Rh;
alternatively, two Ra may join to form a linker selected from (CH2)qO(CH2)q, (CH2)qS(CH2)q, and (CH2)m, wherein the linker is substituted with 0-5 Rh;
Rb, at each occurrence, is independently selected from C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, (CH2)rphenyl, and (CH2)rheterocycle, wherein Rb is substituted with 0-5 Rh;
Rc, at each occurrence, is independently selected from H, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C3-6 cycloalkyl, and (CH2)rphenyl, wherein when Rc is other than H, Rc is substituted with 0-5 Rh;
Rd, at each occurrence, is the residue of an amino acid after the hydroxyl group of the carboxyl group is removed;
Rdxe2x80x2, at each occurrence, is the residue of an amino acid after the hydrogen of the amine is removed;
Re, at each occurrence, is selected from H and C1-6 alkyl;
Rf, at each occurrence, is selected from H, C1-6 alkyl substituted with 0-5 Rh, and (CH2)rphenyl substituted with 0-5 Rh;
Rg, at each occurrence, is selected from C1-6 alkyl substituted with 0-5 Rh and (CH2)rphenyl substituted with 0-5 Rh;
Rh, at each occurrence, is selected from F, Cl, Br, I, OH, NO2, CN, CF3, CF2CF3, C1-4 alkyl, C2-6 alkenyl, C2-6 alkynyl, alkoxy, C3-7 cycloalkyl, carboxyl, formyl, acetyl, propanoyl, butyryl, valeryl, pivaloyl, hexanoyl, acetamido, acetate, carbamyl, carboxy, NH2, monoalkylamino, dialkylamino, phenyl, benzyl, phenethyl, napthyl, heterocycle, and keto;
Ri, at each occurrence, is selected from F, Cl, Br, I, OH, NO2, CN, CF3, CF2CF3, C1-4 alkyl, C2-6 alkenyl, C2-6 alkynyl, alkoxy, C3-7 cycloalkyl, carboxyl, formyl, acetyl, propanoyl, butyryl, valeryl, pivaloyl, hexanoyl, acetamido, acetate, carbamyl, carboxy, NH2, monoalkylamino, dialkylamino, phenyl, benzyl, and phenethyl;
m is selected from 2, 3, 4, and 5;
n is selected from 0, 1, 2, 3, 4, and 5;
p is selected from 0, 1, and 2;
q is selected from 1, 2, 3, and 4; and
r is selected from 0, 1, 2, 3 and 4.
As will be readily understood by the skilled artisan, the position of the double bond in the structure of Formula I will be dependent upon the nature of R5. For example, in certain embodiments wherein R5 is absent, Formula I may have the structure: 
In other embodiments wherein R5 is hydrogen, Formula I may have the tautomeric structure: 
In other embodiments wherein R5 is a substituent, Formula I will have the structure: 
In certain preferred embodiments, Formula I has the formula: 
wherein R1 is selected from hydrogen and alkyl. In other preferred embodiments, R2 or R3 is selected from H and alkyl.
In other preferred embodiments, the heterocyclic substituted pyrazolones are represented by the formula: 
wherein either R2 or R3 is H.
In other preferred embodiments, Het is selected from:
a) a 6-membered heterocyclic ring containing 1 to 3 heteroatoms selected from O, N and S;
b) a 5-membered heterocyclic ring containing either:
1) one oxygen, one nitrogen, or one sulfur atom;
2) a sulfur and a nitrogen atom, an oxygen and a nitrogen atom, or two nitrogen atoms; and
3) three nitrogen atoms, one oxygen and two nitrogen atoms, or one sulfur and two nitrogen atoms;
In other preferred embodiments, Het is heteroaromatic. In other preferred embodiments, Het is selected from: 
wherein X is selected from O, S, NH and N-alkyl.
In other embodiments, Het is non-aromatic. In certain preferred embodiments, Het is selected from: 
In certain embodiments, R4 is selected from F, Cl, Br, I, OH, NO2, CN, CF3, methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, t-butyl, pentyl, ethenyl, propenyl, butenyl, ethynyl, propynyl, butynyl, methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, t-butoxy, phenyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, CO2H, formyl, acetyl, propanoyl, butyryl, NH2, mono- or di-alkylamino, phenyl, heteroaryl, and keto (Cxe2x95x90O). In other preferred embodiments, n is selected from 0, 1, and 2.
In certain embodiments, R3 is a heterocycle selected from:
a) a 6-membered heterocyclic ring containing 1 to 3 heteroatoms selected from O, N and S;
b) a 5-membered heterocyclic ring containing either:
1) one oxygen, one nitrogen, or one sulfur atom;
2) a sulfur and a nitrogen atom, an oxygen and a nitrogen atom, or two nitrogen atoms; and
3) three nitrogen atoms, one oxygen and two nitrogen atoms, or one sulfur and two nitrogen atoms;
In other preferred embodiments, one of R2 or R3 is a heterocycle which is aromatic. In other preferred embodiments, one of R2 or R3 is selected from: 
wherein X is selected from O, S, NH, and N-alkyl.
In other embodiment, one of R2 or R3 is a heterocycle that is non-aromatic. In certain preferred embodiments, one of R2 or R3 is selected from: 
In other embodiments, compounds of Formula I are represented by those set forth in Tables 1 and 1a.
In other embodiments, the present invention provides pharmaceutical compositions comprising a compound of Formula I, a stereoisomer or pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier. In a preferred composition, the compound of Formula I is one set forth in Table 1 or Table 1a.
In other embodiments, the present invention provides a method for inhibiting protein kinase activity comprising providing a compound of Formula I in an amount sufficient to result in effective inhibition. In a preferred embodiment, the kinase receptor is vascular endothelial growth factor receptor (VEGFR) kinase, trkA tyrosine kinase (trkA), mixed lineage kinase (MLK) or fibroplast growth factor receptor kinase (FGFR).
In other embodiments, the present invention provides a method for treating or preventing disorders characterized by the aberrant activity of a protein kinase which comprises administering to a host in need of such treatment or prevention a therapeutically effective amount of a compound of Formula I.
In other embodiments, the present invention provides a method for treating or preventing disorders where either the vascular endothelial growth factor receptor (VEGFR) kinase, trkA tyrosine kinase (trkA), mixed lineage kinase (MLK) or the fibroplast growth factor receptor kinase (FGFR) contributes to pathological conditions, the method comprising providing a compound of Formula I in an amount sufficient to result in the receptor being contacted with an effective inhibitory amount of the compound.
In another embodiment, the present invention provides a method for treating or preventing angiogenic disorders which comprises administering to a host in need of such treatment or prevention a therapeutically effective amount of a compound of Formula I. In a preferred embodiment, the angiogenic disorder is cancer of solid tumors, ocular disorders, macular degeneration, endometriosis, diabetic retinopathy, psoriasis, or hemangioblastoma.
In another embodiment, the present invention provides a method of treating or preventing a disease mediated by a kinase selected from ab1, AKT, bcr-ab1, Blk, Brk, Btk, c-kit, c-met, c-src, CDK1, CDK2, CDK4, CDK6, chk1, chk2, cRaf1, CSF1R, CSK, EGFR, ErbB2, ErbB3, ErbB4, ERK (Eph), Fak, fes, FGFR1, FGFR2, FGFR3, FGFR4, FGFR5, Fgr, FLK-4, flt-1, Fps, Frk, Fyn, GSK, Hck, IGF-1R, INS-R, Jak, JNK, VEGFR1, VEGFR2, VEGFR3, Lck, Lyn, MEK, p38, PDGFR, PIK, PKC, PYK2, ros, tie1, tie2, TRK, UL97, Yes and Zap7O, the method comprising administering to a patient in need of such treatment or prevention a pharmaceutically effective amount of a compound of Formula I.
In other embodiments, the present invention provides a method for treating or preventing disorders where a kinase selected from ab1, AKT, bcr-ab1, Blk, Brk, Btk, c-kit, c-met, c-src, CDK1, CDK2, CDK4, CDK6, chk1, chk2, cRaf1, CSF1R, CSK, EGFR, ErbB2, ErbB3, ErbB4, ERK (Eph), Fak, fes, FGFR1, FGFR2, FGFR3, FGFR4, FGFR5, Fgr, FLK-4, flt-1, Fps, Frk, Fyn, GSK, Hck, IGF-1R, INS-R, Jak, JNK, VEGFR1, VEGFR2, VEGFR3, Lck, Lyn, MEK, p38, PDGFR, PIK, PKC, PYK2, ros, tie1, tie2, TRK, UL97, Yes and Zap70 contributes to pathological conditions, the method comprising providing a compound of Formula I in an amount sufficient to result in the receptor being contacted with an effective inhibitory amount of the compound.
In another embodiment, the present invention provides a method for treating or preventing Alzheimer""s disease, amyotrophic lateral sclerosis, Parkinson""s disease, stroke, ischaemia, Huntington""s disease, AIDS dementia, epilepsy, multiple sclerosis, peripheral neuropathy, injuries of the brain or spinal chord, cancer, restenosis, osteoporosis, inflammation, angiogenesis, viral infections, bone or hematopoetic diseases, autoimmune diseases or transplant rejection which comprises administering to a host in need of such treatment or prevention a therapeutically effective amount of a compound of Formula I.
In certain embodiments, the present invention is directed to inhibition of one or more of Src, raf, and the cyclin-dependent kinases (CDK) 1, 2, and 4 for the treatment of cancer.
In certain embodiments, the present invention is directed to inhibition of one or more of CDK2 or PDGF-R kinase for the treatment of restenosis.
In certain embodiments, the present invention is directed to inhibition of one or more of CDK5 or GSK3 kinases for the treatment of Alzheimers.
In certain embodiments, the present invention is directed to inhibition of one or more of c-Src kinase for the treatment of osteoporosis.
In certain embodiments, the present invention is directed to inhibition of one or more of GSK-3 kinase for the treatment of type-2 diabetes.
In certain embodiments, the present invention is directed to inhibition of one or more of p38 kinase for the treatment of inflammation.
In certain embodiments, the present invention is directed to inhibition of one or more of VEGF-R 1-3, TIE-1, or TIE-2 kinases for the treatment of angiogenesis.
In certain embodiments, the present invention is directed to inhibition of one or more of UL97 kinase for the treatment of viral infections.
In certain embodiments, the present invention is directed to inhibition of one or more of CSF-1R kinase for the treatment of bone and hematopoetic diseases.
In certain embodiments, the present invention is directed to inhibition of one or more of and Lck kinase for the treatment autoimmune diseases and transplant rejection.
In certain embodiment, the present invention provides a method of treating or preventing a disorders mediated by topoisomerases Topo-I or Topo II for the treatment of cancer.
Definitions
The following terms and expressions have the indicated meanings. As used herein xe2x80x9cstable compoundxe2x80x9d or xe2x80x9cstable structurexe2x80x9d is meant to indicate a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and preferably capable of formulation into an efficacious therapeutic agent. The present invention is directed only to stable compounds. As used herein, xe2x80x9csubstitutedxe2x80x9d is intended to indicate that one or more hydrogen atoms on an indicated group is replaced with a selected group referred to herein as a xe2x80x9csubstituentxe2x80x9d, provided that the substituted atom""s valency is not exceeded, and that the substitution results in a stable compound. When the term xe2x80x9csubstitutedxe2x80x9d preceeds a group containing (CH2)r or (CH2)q, for example, (CH2)rphenyl, it is intended that the substituent may reside on the group, i.e., phenyl, or the CH2 chain. By way of illustration, groups which may be further substituted include, but are not limited to, alkyl, alkenyl, alkynyl, alkoxy, acyl, carbocyclic, and heterocyclic, along with additional groups which contain these moieties. A substituted group preferably has 1 to 5 independently selected substituents. Preferred substituents include, but are not limited to F, Cl, Br, I, OH NO2, CN, CF3, CF2CF3, alkyl including, but not limited to, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, and pentyl; alkenyl including but not limited to, ethenyl, propenyl, and butenyl; alkynyl including, but not limited to, ethynyl, propynyl, and butynyl; alkoxy including, but not limited to, methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, and t-butyloxy; cycloalkyl including, but not limited to, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; carboxyl, acyl including, but not limited to, formyl, acetyl, propanoyl, butyryl, valeryl, pivaloyl, and hexanoyl; acetamido, carbamyl, carboxy, hydroxamino, NH2, monoalkylamino, dialkylamino, (CH2)rcarbocycle including, but not limited to, phenyl, phenyl, benzyl, phenethyl, and napthyl; heterocycle, and keto (xe2x95x90O).
As used herein, the term xe2x80x9calkylxe2x80x9d means a straight-chain, or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isoamyl, neopentyl, 1-ethylpropyl, hexyl, octyl. As used herein, xe2x80x9ccycloalkylxe2x80x9d is intended mean monocyclic, bicyclic or tricyclic alkyl groups including, but not limited to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.
As used herein, xe2x80x9calkenylxe2x80x9d is intended to include hydrocarbon chains of either a straight or branched configuration and one or more unsaturated carbon-carbon bonds which may occur in any stable point along the chain, such as ethenyl, propenyl and the like.
As used herein, xe2x80x9calkynylxe2x80x9d is intended to include hydrocarbon chains of either a straight or branched configuration and one or more triple carbon-carbon bonds which may occur in any stable point along the chain, such as ethynyl, propynyl, and the like.
As used herein, xe2x80x9calkoxyxe2x80x9d is intended to include hydrocarbon chains of either straight or branched configuration bonded through an oxygen. Alkoxy includes, but is not limited to methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, t-butyloxy, and the like.
As used herein, xe2x80x9ccarbocyclexe2x80x9d is intended to mean any stable monocyclic, bicyclic or tricyclic ring made up on carbon atoms, which may be saturated, partially unsaturated, or unsaturated. Carbocycles are intended to include, but are not limited to, compounds referred to herein as xe2x80x9ccycloalkylxe2x80x9d. Carbocycles are also intended to include xe2x80x9carylxe2x80x9d or xe2x80x9caromaticxe2x80x9d compounds. Examples of aryl compounds include, but are not limited to phenyl, biphenyl, naphthyl, indanyl, adamantyl, or tetrahydronaphthyl (tetralin).
As used herein, the term xe2x80x9cheterocyclexe2x80x9d or xe2x80x9cheterocyclic ringxe2x80x9d is intended to include a stable monocyclic, bicyclic or tricyclic heterocyclic ring which is saturated, partially unsaturated, or unsaturated rings. Accordingly, heterocycles may be aromatic or non-aromatic. Heterocycles preferably consist of carbon atoms and heteroatoms which are preferably independently selected from the group consisting of N, O and S. The nitrogen and sulfur heteroatoms may optionally be oxidized. The heterocyclic ring may be attached to its pendant group at any heteroatom or carbon atom which results in a stable structure. The heterocycles described herein may be substituted on, for example, a carbon or a nitrogen atom if the resulting compound is stable. If specifically noted, a nitrogen in the heterocycle may optionally be quaternized. It is preferred that when the total number of S and O atoms in the heterocycle exceeds 1, then these heteroatoms are not adjacent to one another. It is preferred that the total number of S and O atoms in the heterocycle is not more than 1.
As used herein, the term xe2x80x9cheteroaromaticxe2x80x9d or xe2x80x9cheteroarylxe2x80x9d is intended to mean a stable heterocycle which is aromatic and consists of carbon atoms and heteroatoms, wherein the heteroatoms are preferably independently selected from the group consisting of N, O and S.
Examples of heterocycles include, but are not limited to, 2-pyrrolidonyl, 2H-pyrrolyl, 4-piperidonyl, 6H-1,2,5-thiadiazinyl, 2H,6H-1,5,2-dithiazinyl, furanyl, furazanyl, imidazolidinyl, imidazolinyl, imidazolyl, isoxazolyl, morpholinyl, oxadiazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl., oxazolyl, piperazinyl, piperidinyl, pteridinyl, piperidonyl, 4-piperidonyl, pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, pyrrolyl, tetrahydrofuranyl, 6H-1,2,5-thiadiazinyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, thiazolyl, thienyl, thienothiazolyl, thienooxazolyl, thienoimidazolyl, thiophenyl, triazinyl, 1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl, and tetrazole. Also included are fused ring and spiro compounds containing, for example, the above heterocycles. Suitable heterocycles are also disclosed in The Handbook of Chemistry and Physics, 76th Edition, CRC Press, Inc., 1995-1996, pages 2-25 to 2-26, the disclosure of which is hereby incorporated by reference.
Preferred heterocyclic groups formed with a nitrogen atom include, but are not limited to, pyrrolidinyl, piperidinyl, piperidino, morpholinyl, morpholino, thiomorpholino, N-methylpiperazinyl, indolyl, isoindolyl, imidazole, imidazoline, oxazoline, oxazole, triazole, thiazoline, thiazole, isothiazole, thiadiazoles, triazines, isoxazole, oxindole, indoxyl, pyrazole, pyrazolone, pyrimidine, pyrazine, quinoline, iosquinoline, and tetrazole groups.
Preferred heterocyclic groups formed with an oxygen atom include, but are not limited to, furan, tetrahydrofuran, pyran, benzofurans, isobenzofurans, and tetrahydropyran groups. Preferred heterocyclic groups formed with a sulfur atom include, but are not limited to, thiophene, thianaphthene, tetrahydrothiophene, tetrahydrothiapyran, and benzothiophenes.
Preferred heteroaryl groups include, but are not limited to, pyridyl, pyrimidyl, pyrrolyl, furyl, thienyl, imidazolyl, triazolyl, tetrazolyl, quinolyl, isoquinolyl, benzoimidazolyl, thiazolyl, pyrazolyl, and benzothiazolyl groups.
As used herein, the term xe2x80x9cmonosaccharidexe2x80x9d has its accustomed meaning as a simple sugar. As used herein, the term xe2x80x9camino acidxe2x80x9d denotes a molecule containing both an amino group and a carboxyl group. Embodiments of amino acids include xcex1-amino, xcex2-amino, xcex3-amino acids. As used herein, xe2x80x9cxcex1-amino acidsxe2x80x9d are carboxylic acids of general formula HOOCxe2x80x94CH(NH2)-(side chain). Side chains of amino acids include naturally occurring and non-naturally occurring moieties. Non-naturally occurring (i.e., unnatural) amino acid side chains are moieties that are used in place of naturally occurring amino acid side chains in, for example, amino acid analogs. See, for example, Lehninger, Biochemistry, Second Edition, Worth Publishers, Inc, 1975, pages 73-75, the disclosure of which is incorporated herein by reference. In certain embodiments, substituent groups of formula Rd include the residue of an amino acid after removal of the hydroxyl moiety of the carboxyl group thereof; i.e., groups of Formula xe2x80x94C(xe2x95x90O)CH-(side chain)-NHRxe2x80x2, wherein Rxe2x80x2 is H, C1-6 alkyl, or an amine protecting group. In certain embodiments, substituent groups of formula Rdxe2x80x2 include the residue of an amino acid after removal of the hydrogen of the amine group thereof; i.e., groups of Formula xe2x80x94NHxe2x80x94CH-(side chain)-C(xe2x95x90O)ORxe2x80x2, wherein Rxe2x80x2 is H, C1-6 alkyl, or a carboxyl protecting group.
Functional groups present on the compounds of Formula I or intermediate compounds may also contain protecting groups. Preferred protecting groups include the benzyloxycarbonyl (Cbz; Z) group and the tert-butyloxycarbonyl (Boc) group. Other preferred protecting groups may be found in Greene, T. W. and Wuts, P. G. M., Protective Groups in Organic Synthesis 2d. Ed., Wiley and Sons, 1991, a common text in the field, the disclosure of which is incorporated herein by reference.
As used herein, terms commonly used to describe the effects of therapeutic agents in biological systems, assays, and the like, are intended to have their art-recognized meanings. As used herein, the term xe2x80x9ceffectxe2x80x9d when used to modify the terms xe2x80x9cfunctionxe2x80x9d and xe2x80x9csurvivalxe2x80x9d means a positive or negative alteration or change. An effect which is positive may be referred to herein as an xe2x80x9cenhancementxe2x80x9d or xe2x80x9cenhancingxe2x80x9d, and an effect which is negative may be referred to herein as xe2x80x9cinhibitionxe2x80x9d or xe2x80x9cinhibiting.xe2x80x9d
As used herein, the terms xe2x80x9cenhancexe2x80x9d or xe2x80x9cenhancingxe2x80x9d when used to modify the terms xe2x80x9cfunctionxe2x80x9d or xe2x80x9csurvivalxe2x80x9d means that the presence of an heterocyclic substituted pyrazolone compound has a positive effect on the function and/or survival of a trophic factor responsive cell compared with a cell in the absence of the compound. For example, and without limitation, with respect to the survival of, e.g., a cholinergic neuron, the compound would evidence enhancement of survival of a cholinergic neuronal population at risk of dying (due to, e.g., injury, a disease condition, a degenerative condition or natural progression) when compared to a cholinergic neuronal population not presented with such compound, if the treated population has a comparatively greater period of functionality than the non-treated population. As used herein, xe2x80x9cinhibitxe2x80x9d and xe2x80x9cinhibitionxe2x80x9d mean that a specified response of a designated material (e.g., enzymatic activity) is comparatively decreased in the presence of a heterocyclic substituted pyrazolone compound.
As used herein, the term xe2x80x9ctrkxe2x80x9d refers to the family of high affinity neurotrophin receptors presently comprising trk A, trk B, and trk C, and other membrane associated proteins to which a neurotrophin can bind.
As used herein, the terms xe2x80x9ccancerxe2x80x9d and xe2x80x9ccancerousxe2x80x9d refer to any malignant proliferation of cells in a mammal. Examples include prostate, benign prostate hyperplasia, ovarian, breast, brain, lung, pancreatic, colorectal, gastric, stomach, solid tumors, head and neck, neuroblastoma, renal cell carcinoma, lymphoma, leukemia, other recognized malignancies of the hematopoietic systems, and other recognized cancers.
As used herein the terms xe2x80x9cneuron,xe2x80x9d xe2x80x9ccell of neuronal lineagexe2x80x9d and xe2x80x9cneuronal cellxe2x80x9d include, but are not limited to, a heterogeneous population of neuronal types having singular or multiple transmitters and/or singular or multiple functions; preferably, these are cholinergic and sensory neurons. As used herein, the phrase xe2x80x9ccholinergic neuronxe2x80x9d means neurons of the Central Nervous System (CNS) and Peripheral Nervous System (PNS) whose neurotransmitter is acetylcholine; exemplary are basal forebrain, striatal, and spinal cord neurons. As used herein, the phrase xe2x80x9csensory neuronxe2x80x9d includes neurons responsive to environmental cues (e.g., temperature, movement) from, e.g., skin, muscle and joints; exemplary is a neuron from the dorsal root ganglion.
As used herein, a xe2x80x9ctrophic factor-responsive cell,xe2x80x9d is a cell which includes a receptor to which a trophic factor can specifically bind; examples include neurons (e.g., cholinergic and sensory neurons) and non-neuronal cells (e.g., monocytes and neoplastic cells).
As used herein, a xe2x80x9ctherapeutically effective amountxe2x80x9d refers to an amount of a compound of the present invention effective to prevent or treat the symptoms of particular disorder. Such disorders include, but are not limited to, those pathological and neurological disorders associated with the aberrant activity of the receptors described herein, wherein the treatment or prevention comprises inhibiting, inducing, or enhancing the activity thereof by contacting the receptor with a compound of Formula I.
As used herein, the term xe2x80x9cpharmaceutically acceptablexe2x80x9d refers to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem complications commensurate with a reasonable benefit/risk ration.
As used herein, xe2x80x9cpharmaceutically acceptable saltsxe2x80x9d refer to derivatives of the disclosed compounds wherein the parent compound is modified by making acid or base salts thereof. Examples of pharmaceutically acceptable salts include, but are not limited to, mineral or organic acid salts of basic residues such as amines; alkali or organic salts of acidic residues such as carboxylic acids; and the like. The pharmaceutically acceptable salts include the conventional non-toxic salts or the quaternary ammonium salts of the parent compound formed, for example, from non-toxic inorganic or organic acids. For example, such conventional non-toxic salts include those derived from inorganic acids such as hydrochloric, hydrobromic, sulfuric, sulfamic, phosphoric, nitric and the like; and the salts prepared from organic acids such as acetic, propionic, succinic, glycolic, stearic, lactic, malic, tartaric, citric, ascorbic, pamoic, maleic, hydroxymaleic, phenylacetic, glutamic, benzoic, salicylic, sulfanilic, 2-acetoxybenzoic, fumaric, toluenesulfonic, methanesulfonic, ethane disulfonic, oxalic, isethionic, and the like.
The pharmaceutically acceptable salts of the present invention can be synthesized from the parent compound which contains a basic or acidic moiety by conventional chemical methods. Generally, such salts can be prepared by reacting the free acid or base forms of these compounds with a stoichiometric amount of the appropriate base or acid in water or in an organic solvent, or in a mixture of the two. Generally, nonaqueous media like ether, ethyl acetate, ethanol, isopropanol, or acetonitrile are preferred. Lists of suitable salts are found in Remington""s Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa., 1985, p. 1418, the disclosure of which is hereby incorporated by reference.
As used herein, xe2x80x9cprodrugxe2x80x9d is intended to include any covalently bonded carriers which release the active parent drug according to Formula (I) or other formulas or compounds of the present invention in vivo when such prodrug is administered to a mammalian subject. Since prodrugs are known to enhance numerous desirable qualities of pharmaceuticals (e.g., solubility, bioavailability, manufacturing, etc.) the compounds of the present invention may be delivered in prodrug form. Thus, the present invention contemplates prodrugs of the claimed compounds, compositions containing the same, and methods of delivering the same.
Prodrugs of a compound of the present invention, for example Formula I, may be prepared by modifying functional groups present in the compound in such a way that the modifications are cleaved, either in routine manipulation or in vivo, to the parent compound. Accordingly, prodrugs include, for example, compounds of the present invention wherein a hydroxy, amino, or carboxy group is bonded to any group that, when the prodrug is administered to a mammalian subject, cleaves to form a free hydroxyl, free amino, or carboxylic acid, respectively. Examples include, but are not limited to, acetate, formate and benzoate derivatives of alcohol and amine functional groups; and alkyl, carbocyclic, aryl, and alkylaryl esters such as methyl, ethyl, propyl, iso-propyl, butyl, isobutyl, sec-butyl, tert-butyl, cyclopropyl, phenyl, benzyl, and phenethyl esters, and the like.
Synthesis
The compounds of the present invention may be prepared in a number of ways well known to those skilled in the art. The compounds can be synthesized, for example, by the methods described below, or variations thereon as appreciated by the skilled artisan. All processes disclosed in association with the present invention are contemplated to be practiced on any scale, including milligram, gram, multi-gram, kilogram, multi-kilogram or commercial industrial scale.
It will be appreciated that the compounds of the present invention may contain one or more asymmetrically substituted carbon atoms, and may be isolated in optically active or racemic forms. Thus, all chiral, diastereomeric, racemic forms and all geometric isomeric forms of a structure are intended, unless the specific stereochemistry or isomeric form is specifically indicated. It is well known in the art how to prepare and isolate such optically active forms. For example, mixtures of stereoisomers may be separated by standard techniques including, but not limited to, resolution of racemic forms, normal, reverse-phase, and chiral chromatography, preferential salt formation, re-crystallization, and the like, or by chiral synthesis either from chiral starting materials or by deliberate generation of target chiral centers.
As will be readily understood, functional groups present on the compounds of Formula I may contain protecting groups during the course of synthesis. For example, the amino acid side chain substituents of the compounds of Formula I can be substituted with protecting groups such as benzyloxycarbonyl or t-butoxycarbonyl groups. Protecting groups are known per se as chemical functional groups that can be selectively appended to and removed from functionalities, such as hydroxyl groups and carboxyl groups. These groups are present in a chemical compound to render such functionality inert to chemical reaction conditions to which the compound is exposed. Any of a variety of protecting groups may be employed with the present invention. Preferred protecting groups include the benzyloxycarbonyl (Cbz; Z) group and the tert-butyloxycarbonyl (Boc) group. Other preferred protecting groups according to the invention may be found in Greene, T. W. and Wuts, P. G. M., Protective Groups in Organic Synthesis 2d. Ed., Wiley and Sons, 1991.
Compounds having formula (I-i) or (I-ii): 
may be prepared, for example, as described in Schemes 1 through 6. For certain embodiments, the xcex2-ketoester (V) serves as a key intermediate to I-i and I-ii. 
In certain embodiments, compounds of the present invention may contain heterocycles, which are further substituted. Heterocyclic compounds which are further substituted (including additional heterocycles) may be obtained by a variety of methods known to those skilled in the art. Starting materials as well as methods which may be used for the synthesis of xcex2-ketoester intermediate (V) are described, for example, by Thompson and Gaudino, J. Org. Chem. 1984, 49, 5237-5243; an d by Kamal M. R. et. al., Phosphorous, Sulfur, Silicon Relat. Elem. 1997, 126, 65-74; the disclosures of which are incorporated herein by reference in their entirety.
Generally, compounds of formula (V) may be prepared, for example, by methods set forth in Scheme 1. 
Reaction of a heterocyclic methyl ester, acid halide or imidazolide (III), with an ester enolate, affords compound (V) (Scheme 1a). Similar methods are taught, for example, in Bunting, J. W.; Kanter, J. P., J. Am. Chem. Soc., 1993, 115, 11705-11715, the disclosure of which is incorporated herein by reference in its entirety. By way of further guidance, to a solution of heterocyclic carboxylic ester (III) (1 equiv.) in methyl acetate (0.5-1 mL/mmol of the ester) may be added NaH (60% dispersion in mineral oil, 1.1 equiv.) with continuous stirring for approximately 0.5 hours. The reaction mixture is preferably stirred under reflux for about 2.5 hours, cooled to room temperature, poured to water (1 ml/mmol of the ester), and extracted from a suitable solvent such as diethyl ether. The aqueous layer may be neutralized with concentrated acid and extracted repeatedly with a polar solvent such as methylene chloride. The combined organic layers are preferably combined and concentrated in vacuo to provide the crude xcex2-ketoester (V), which may be used for pyrazolone formation without further purification.
Alternatively, compounds of formula (V) may be prepared by carboxy-alkylation of a heterocyclic methyl ketone, using a dialkyl carbonate (Scheme 1b). The synthesis of xcex2-ketoesters prepared in this manner are also described, for example, in Krapcho, A. P.; Diamanti, J.; Cayen, C.; Bingham, R., Org. Synth. 1973, 5, 198-201, the disclosure of which is incorporated herein by reference in its entirety. By way of further guidance, to a vigorously stirred suspension of NaH (2.9 equiv.) and diethyl carbonate (2 equiv.) in dry toluene (1.5 mL/mmol of the methyl ketone) may be added dropwise a solution of the desired heterocyclic methyl ketone (II) (1 equiv.) in toluene under reflux. After addition, the mixture may be stirred at reflux for approximately 0.5 hour. The mixture is preferably cooled to room temperature and acidified with a suitable acid, such as glacial acetic acid. After addition of cold water, the mixture may be extracted from a suitable solvent, such as toluene. After work up, the solvent may be evaporated to furnish the crude xcex2-ketoester, (V), which may be used for pyrazolone formation without further purification.
Intermediate (V) may also be obtained from a heterocyclic compound (IV) following metalation and reaction with ethyl propinyl chloride (Scheme 1c). This method is further described by Morales-Rios, et. al, Heterocycles, 1996, 43, 1483-96, the disclosure of which is incorporated herein by reference in its entirety.
The xcex2-ketoester (V), prepared by any of the foregoing methods may be reacted, for example, with various hydrazine derivatives (Scheme 2). 
Reaction with hydrazine provides 4-unsubstituted pyrazolones (VI) (Scheme 2a). By way of further guidance, to a mixture of xcex2-ketoester (V) in absolute ethanol (3-5 mL/mmol of xcex2-ketoester) may be added hydrazine hydrate (5-10-fold excess) and the mixture kept under reflux for approximately 3-5 hours. The mixture is preferably cooled to room temperature and the solvent was evaporated. The pyrazolone may be isolated by filtration (if solid separation was noticed) or flash chromatography using an appropriate chromatographic solvent system such as EtOAc/methanol. Subsequent tituration with ether or ethyl acetate may help aid in further purification. The 4-unsubstituted pyrazolones (VI) may also be obtained by reaction of a heterocylic propargyl ester (VII) with excess hydrazine (Scheme 2b).
Upon Knoevenagel condensation with appropriately substituted carbonyl compounds, the pyrazolone (VI) provides the desired pyrazolone analogs (I-i) (Scheme 3). 
By way of further guidance, a mixture of the appropriate pyrazolone (1 equiv.) and the desired aldehyde (1.1 equiv.) in absolute ethanol (2.5-3 mL/mmol of pyrazolone) may be stirred at 80-90xc2x0 C. for approximately 1 to 5 hours. The product that separates as a solid (either from hot reaction mixture or upon subsequent cooling in ice bath) may be isolated by filtration and washed with small amounts of a protic solvent such as ethanol. NMR of the solid preferably shows one geometrical isomer. Other methods are taught, for example, in the text Organic Synthesis, G. Jones, edited by R. Adams, John Wiley and Sons, INC., New York, 1967, pp 204-599, the disclosure of which is incorporated herein by reference in its entirety.
Alternatively, the xcex2-ketoester (V) may be first condensed with an appropriately substituted carbonyl compound to provide intermediate (VIII), which may be subsequently converted to the pyrazolone (I-i) (Scheme 4). 
The pyrazolone derivative bearing the R5 substituents may be obtained by the reaction of mono-substituted hydrazine (or disubstituted hydrazine, e.g. when R1 not hydrogen is desired) either with a xcex2-ketoester (V) or the acetylenic derivative (VII) (Schemes 5a and 5b, respectively). The substituent at the 4 position may then be introduced, for example, with an aldehyde and a secondary amine (Scheme 5c). Compounds wherein R2 is a heterocycle attached through a heteroatom may be prepared, for example, by reacting compound (XI) with formaldehyde in the presence of a nucleophilic heterocycle (Scheme 5d). 
Alternatively, the xcex2-ketoester (X), already bearing a substituent, may be subsequently converted to the pyrazolone analogs (I-ii). Compound (X) may be prepared, for example, by reaction of a heterocyclic methyl ester, acid halide or imidazolide (III), with an appropriately substituted ester enolate (Scheme 6a). Alternatively, compound (X) may be prepared by deprotonating a heterocyclic xcex2-ketoester and reacting the enolate with an appropriately substituted alkyl halide, alkyl mesylate, or the like (Scheme 6b). 
Compounds of Formula (I-ii) and/or (I-iii) may also be prepared, for example, from pyrazolone (I-i), upon treatment with an appropriate reducing agent, such as NaBH4, LiBH4, and the like (Scheme 7). As will be appreciated by one skilled in the art, compounds of Formula (I-ii) or (I-iii) may be further reacted under suitable conditions to add R5 groups, wherein R5 is other than hydrogen. 
Other features of the invention will become apparent in the course of the following descriptions of exemplary embodiments. These examples are given for illustration of the invention and are not intended to be limiting thereof